Meningiomas

Meningiomas are typically benign, slow-growing tumors that arise from the meninges. The meninges are a protective membrane surrounding the brain and spinal cord. These tumors do not arise from the brain itself but instead grow inward from the meninges exerting pressure on the brain or spinal cord. Occasionally meningiomas will grow outwards into the skull, causing it to thicken. Although most meningiomas are benign slow growing tumors, higher-grade (Atypical and Malignant) meningiomas can occur in a small minority of patients. Meningiomas, in general, are relatively common tumors, making up about 30% percent of all primary brain tumors, and can occur anywhere on the meninges. The tumors can occur in anyone, but they appear to be most common in middle-aged women.

It is common to name meningiomas based on the location of the tumor in relation to the overlying skull. For example a simple convexity meningioma lies under the side of the skull whereas a parasagittal meningioma is located near the sagittal sinus, a major blood vessel at the top of the cerebral hemispheres. Some meningiomas grow at the bottom of the skull and are called skull base meningiomas with specific names related to the adjacent bony structure. These tumors can cause problems even though they are benign because of pressure exerted on the surrounding nerves and brain.

Symptoms

Meningiomas are usually slow growing and, therefore, may grow to a large size before causing symptoms. The symptoms of a meningioma are caused by the pressure the growing tumor exerts on surrounding brain. These tumors can occur in a variety of places and therefore cause a wide range of symptoms, although they tend to occur in specific regions around the brain. Depending on the location of the mass, meningiomas may cause headaches, nausea, seizures, weakness or numbness in the limbs or face, visual problems, and gradual changes in mood or personality. The symptoms tend to increase in severity as the tumor grows in size.

Diagnosis

Meningiomas are usually slow growing and, therefore, may grow to a large size before causing symptoms. The symptoms of a meningioma are caused by the pressure the growing tumor exerts on surrounding brain. These tumors can occur in a variety of places and therefore cause a wide range of symptoms, although they tend to occur in specific regions around the brain. Depending on the location of the mass, meningiomas may cause headaches, nausea, seizures, weakness or numbness in the limbs or face, visual problems, and gradual changes in mood or personality. The symptoms tend to increase in severity as the tumor grows in size.

Treatment

If a particular meningioma is small and does not cause any symptoms, it may be observed over time rather than treated immediately. In this situation surveillance MRI scans will be recommended to monitor the stability of the tumor over time. In cases in which treatment is necessary, surgery is usually the primary form of treatment for a meningioma. Because most meningiomas are benign, and rarely invade the surrounding brain tissue, complete resection often results in a cure. Prior to surgery, some patients can benefit from embolization of the blood supply to a meningioma which can make complete removal easier for the surgeon. Usually surgery is performed with a frameless stereotactic navigation system in which a high-resolution MRI is used to construct a 3-dimensional brain model – much like a GPS system – that allows for minimally invasive surgery. High-powered microscopes are also used to help the neurosurgeon better see the tumor and ultrasonic aspirators are sometimes used to help remove the tumor. Some tumors, however, may be difficult to remove completely, especially those that occur near important structures at the base of the skull. After surgery, the tumor tissue is microscopically examined to establish an accurate diagnosis, assess the risk of recurrence and dictate the next step in treatment.

Conventional external beam radiation therapy may be used as a follow-up treatment, especially for malignant or atypical tumors that have recurred. In addition, non-invasive, stereotactic radiosurgery (CyberKnife and Gamma Knife) may be used as either primary or adjunct treatment for small or residual tumors in difficult to reach locations or in patients that cannot undergo surgery. Stereotactic Radiosurgery uses numerous finely focused beams of radiation to accurately target the tumor and while minimizing the effects to any surrounding tissue. The target tumor is usually outlined on a 3-Dimensional model of the brain by the neurosurgeon and the radiation oncologist prior to the procedure.

After surgery, each patient is reviewed at our Multi-Disciplinary Tumor Board with an expert team of neuro-oncologists, medical oncologists, neuro-pathologists, neuro-radiologists and neurosurgeons. Together the tumor board recommends the best treatment options for each patient, incorporating ongoing national clinical trials and the latest treatment protocols.